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We address a debate over the effects of private versus customary property rights on external investment. Despite political economists’ claims that external investors favor private property rights, other experts argue that customary systems enable large-scale “land grabs.” We organize these competing claims, highlighting trade-offs due to differences in legibility versus the ability to displace existing landholders under both systems. We study a natural experiment in Liberia, where law codifies parallel private and customary property rights systems. We use this institutional boundary and difference-in-differences methods to isolate differential changes in external investment under the different property rights systems following the global food crisis of 2007–08. We find a larger increase in land clearing where private property rights prevailed, with such clearing related to more concession activity. Qualitative study of a palm oil concession reveals challenges external investors confront when navigating customary systems.
Ecosystem modeling, a pillar of the systems ecology paradigm (SEP), addresses questions such as, how much carbon and nitrogen are cycled within ecological sites, landscapes, or indeed the earth system? Or how are human activities modifying these flows? Modeling, when coupled with field and laboratory studies, represents the essence of the SEP in that they embody accumulated knowledge and generate hypotheses to test understanding of ecosystem processes and behavior. Initially, ecosystem models were primarily used to improve our understanding about how biophysical aspects of ecosystems operate. However, current ecosystem models are widely used to make accurate predictions about how large-scale phenomena such as climate change and management practices impact ecosystem dynamics and assess potential effects of these changes on economic activity and policy making. In sum, ecosystem models embedded in the SEP remain our best mechanism to integrate diverse types of knowledge regarding how the earth system functions and to make quantitative predictions that can be confronted with observations of reality. Modeling efforts discussed are the Century ecosystem model, DayCent ecosystem model, Grassland Ecosystem Model ELM, food web models, Savanna model, agent-based and coupled systems modeling, and Bayesian modeling.
Multiple predictors have been associated with persistent somatic symptoms. However, previous studies problematically defined the persistence of symptoms, conflated participants' sex and gender, and focused on patient populations. Therefore, we studied associations between predictors, especially sex and gender, and longitudinal patterns of somatic symptoms in the general adult population. We also assessed whether predictors for persisting symptoms differ between sexes.
To identify developmental trajectories of somatic symptoms, assessed by the SCL-90 SOM, we used latent class trajectory modeling in the Dutch Lifelines Cohort Study [N = 150 494; 58.6% female; median time to follow-up: 46.0 (min–max: 22.0–123.0) months]. To identify predictors of trajectories, we applied multiple logistic regression analyses. Predictors were measured by surveys at baseline and a composite gender index was previously developed.
A five-class linear LCGA model fitted the data best: 93.7% of the population had a stable symptom trajectory, whereas 1.5% and 4.8% of the population had a consistently increasing or decreasing symptom trajectory, respectively. Female sex predicted severe, stable symptom severity (OR 1.74, 95% CI 1.36–2.22), but not increasing symptom severity (OR 1.15, 95% CI 0.99–1.40). Femininity was protective hereof (OR 0.60, 95% CI 0.44–0.82 and OR 0.66, 95% CI 0.51–0.85, respectively). Merely a few predictors of symptom severity, for instance hours of paid employment and physical functioning, differed in strength between sexes. Yet, effect sizes were small.
Female sex and femininity predict symptom trajectories. No large sex differences in the strength of additional predictors were found, thus it may not be clinically useful to distinguish between predictors specific to male or female patients of persistent somatic symptoms.
Empirical studies on the clinical characteristics of older persons with medically unexplained symptoms are limited to uncontrolled pilot studies. Therefore, we aim to examine the psychiatric characteristics of older patients with medically unexplained symptoms (MUS) compared to older patients with medically explained symptoms (MES), also across healthcare settings.
A case–control study including 118 older patients with MUS and 154 older patients with MES. To include patients with various developmental and severity stages, patients with MUS were recruited in the community (n = 12), primary care (n = 77), and specialized healthcare (n = 29). Psychopathology was assessed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) criteria (Mini-International Neuropsychiatric Interview) and by dimensional measures (e.g., psychological distress, hypochondriasis, and depressive symptoms).
A total of 69/118 (58.5%) patients with MUS met the criteria for a somatoform disorder according to DSM-IV-TR criteria, with the highest proportion among patients recruited in specialized healthcare settings (p = 0.008). Patients with MUS had a higher level of psychological distress and hypochondriasis compared to patients with MES. Although psychiatric disorders (beyond somatoform disorders) were more frequently found among patients with MUS compared to patients with MES (42.4 vs. 24.8%, p = 0.008), this difference disappeared when adjusted for age, sex, and level of education (odds ratio = 1.7 [95% confidence interval: 1.0–3.0], p = 0.070).
Although psychological distress is significantly higher among older patients with MUS compared to those with MES, psychiatric comorbidity rates hardly differ between both patient groups. Therefore, treatment of MUS in later life should primarily focus on reducing psychological distress, irrespective of the healthcare setting patients are treated in.
Major depressive disorder (MDD) is a common mood disorder, with a heritability of around 34%. Molecular genetic studies made significant progress and identified genetic markers associated with the risk of MDD; however, progress is slowed down by substantial heterogeneity as MDD is assessed differently across international cohorts. Here, we used a standardized online approach to measure MDD in multiple cohorts in the Netherlands and evaluated whether this approach can be used in epidemiological and genetic association studies of depression.
Within the Biobank Netherlands Internet Collaboration (BIONIC) project, we collected MDD data in eight cohorts involving 31 936 participants, using the online Lifetime Depression Assessment Self-report (LIDAS), and estimated the prevalence of current and lifetime MDD in 22 623 unrelated individuals. In a large Netherlands Twin Register (NTR) twin-family dataset (n ≈ 18 000), we estimated the heritability of MDD, and the prediction of MDD in a subset (n = 4782) through Polygenic Risk Score (PRS).
Estimates of current and lifetime MDD prevalence were 6.7% and 18.1%, respectively, in line with population estimates based on validated psychiatric interviews. In the NTR heritability estimates were 0.34/0.30 (s.e. = 0.02/0.02) for current/lifetime MDD, respectively, showing that the LIDAS gives similar heritability rates for MDD as reported in the literature. The PRS predicted risk of MDD (OR 1.23, 95% CI 1.15–1.32, R2 = 1.47%).
By assessing MDD status in the Netherlands using the LIDAS instrument, we were able to confirm previously reported MDD prevalence and heritability estimates, which suggests that this instrument can be used in epidemiological and genetic association studies of depression.
Dietary quality (DQ), as assessed by the Alternative Healthy Eating Index for Pregnancy (AHEI-P), and conception and pregnancy outcomes were evaluated.
In this prospective cohort study on couples planning their first pregnancy. Cox proportional hazards regression assessed the relationship between AHEI-P score and clinical pregnancy, live birth and pregnancy loss.
Participants were recruited from the Northeast region of the USA.
Participants: Healthy, nulliparous couples (females, n 132; males, n 131; one male did not enrol).
There were eighty clinical pregnancies, of which sixty-nine resulted in live births and eleven were pregnancy losses. Mean (sd) female AHEI-P was 71·0 (13·7). Of those who achieved pregnancy, those in the highest tertile of AHEI-P had the greatest proportion of clinical pregnancies; however, this association was not statistically significant (P = 0·41). When the time it took to conceive was considered, females with the highest AHEI-P scores were 20 % and 14 % more likely to achieve clinical pregnancy (model 1: hazard ratio (HR) = 1·20; 95 % CI 0·66, 2·17) and live birth (model 1: HR = 1·14; 95 % CI 0·59, 2·20), respectively. Likelihood of achieving clinical pregnancy and live birth increased when the fully adjusted model, including male AHEI-P score, was examined (clinical pregnancy model 4: HR = 1·55; 95 % CI 0·71, 3·39; live birth model 4: HR = 1·36; 95 % CI 0·59, 3·13).
The present study is the first to examine AHEI-P score and achievement of clinical pregnancy. DQ was not significantly related to pregnancy outcomes, even after adjustments for covariates.
Various childhood social experiences have been reported to predict adult outcomes. However, it is unclear how different social contexts may influence each other's effects in the long run. This study examined the joint contribution of adolescent family and peer experiences to young adult wellbeing and functioning.
Participants came from the TRacking Adolescents’ Individual Lives Survey (TRAILS) study (n = 2230). We measured family and peer relations at ages 11 and 16 (i.e. family functioning, perceived parenting, peer status, peer relationship quality), and functioning as the combination of subjective wellbeing, physical and mental health, and socio-academic functioning at age 22. Using structural equation modelling, overall functioning was indicated by two latent variables for positive and negative functioning. Positive, negative and overall functioning at young adulthood were regressed on adolescent family experiences, peer experiences and interactions between the two.
Family experiences during early and mid-adolescence were most predictive for later functioning; peer experiences did not independently predict functioning. Interactions between family and peer experiences showed that both protective and risk factors can have context-dependent effects, being exacerbated or overshadowed by negative experiences or buffered by positive experiences in other contexts. Overall the effect sizes were modest at best.
Adolescent family relations as well as the interplay with peer experiences predict young adult functioning. This emphasizes the importance of considering the relative effects of one context in relation to the other.
We modeled both psychopathology and executive function (EF) as bi-factor models to study if EF impairments are transdiagnostic or relate to individual syndromes, and concurrently, if such associations are with general EF or specific EF impairments.
Data were obtained from the Tracking Adolescents’ Individual Lives Survey (TRAILS; N = 2230). Psychopathology was assessed with parent-report questionnaires at ages 11, 14, 16, and 19, and EF with tasks from the Amsterdam Neuropsychological Tasks program at ages 11 and 19. Bi-factor models were fitted to the data using confirmatory factor analysis. Correlations were estimated to study the associations between general or specific components of both psychopathology and EF.
A bi-factor model with a general psychopathology factor, alongside internalizing (INT), externalizing, attention deficit/hyperactivity (ADHD), and autism spectrum (ASD) problem domains, and a bi-factor model with a general EF factor, alongside specific EFs were adequately fitting measurement models. The best-fitting model between EF and psychopathology showed substantial associations of specific EFs with the general psychopathology factor, in addition to distinct patterns of association with ASD, ADHD, and INT problems.
By studying very diverse psychopathology domains simultaneously, we show how EF impairments cross diagnostic boundaries. In addition to this generic relation, ADHD, ASD, and INT symptomatology show separable profiles of EF impairments. Thus, inconsistent findings in the literature may be explained by substantial transdiagnostic EF impairments. Whether general EF or specific EFs are related to psychopathology needs to be further studied, as differences in fit between these models were small.
In regions plagued by reoccurring periods of war, violence and displacement, how does past exposure to violence affect altruism toward members of different ethnic or religious groups? Drawing on theories of empathy-driven altruism in psychology, this article proposes that violence can increase individuals’ capacity to empathize with others, and that empathy born of violence can in turn motivate helping behavior across group boundaries. This hypothesis is tested using data on the hosting behavior of roughly 1,500 Liberians during the 2010–11 Ivorian refugee crisis in eastern Liberia, a region with a long history of cross-border, inter-ethnic violence. Consistent with its theoretical predictions, the study finds that those who experienced violence during the Liberian civil war host greater numbers of refugees, exhibit stronger preferences for distressed refugees and less bias against outgroup refugees, and host a higher proportion of non-coethnic, non-coreligious and distressed refugees. These findings suggest that violence does not necessarily lead to greater antagonism toward outgroups, as is often assumed, and that in some circumstances it can actually promote inter-group co-operation.
Various sources indicate that mental disorders are the leading contributor to the burden of disease among youth. An important determinant of functioning is current mental health status. This study investigated whether psychiatric history has additional predictive power when predicting individual differences in functional outcomes.
We used data from the Dutch TRAILS study in which 1778 youths were followed from pre-adolescence into young adulthood (retention 80%). Of those, 1584 youths were successfully interviewed, at age 19, using the World Health Organization Composite International Diagnostic Interview (CIDI 3.0) to assess current and past CIDI-DSM-IV mental disorders. Four outcome domains were assessed at the same time: economic (e.g. academic achievement, social benefits, financial difficulties), social (early motherhood, interpersonal conflicts, antisocial behavior), psychological (e.g. suicidality, subjective well-being, loneliness), and health behavior (e.g. smoking, problematic alcohol, cannabis use).
Out of the 19 outcomes, 14 were predicted by both current and past disorders, three only by past disorders (receiving social benefits, psychiatric hospitalization, adolescent motherhood), and two only by current disorder (absenteeism, obesity). Which type of disorders was most important depended on the outcome. Adjusted for current disorder, past internalizing disorders predicted in particular psychological outcomes while externalizing disorders predicted in particular health behavior outcomes. Economic and social outcomes were predicted by a history of co-morbidity of internalizing and externalizing disorder. The risk of problematic cannabis use and alcohol consumption dropped with a history of internalizing disorder.
To understand current functioning, it is necessary to examine both current and past psychiatric status.
In search of empirical classifications of depression and anxiety, most subtyping studies focus solely on symptoms and do so within a single disorder. This study aimed to identify and validate cross-diagnostic subtypes by simultaneously considering symptoms of depression and anxiety, and disability measures.
A large cohort of adults (Lifelines, n = 73 403) had a full assessment of 16 symptoms of mood and anxiety disorders, and measurement of physical, social and occupational disability. The best-fitting subtyping model was identified by comparing different hybrid mixture models with and without disability covariates on fit criteria in an independent test sample. The best model's classes were compared across a range of external variables.
The best-fitting Mixed Measurement Item Response Theory model with disability covariates identified five classes. Accounting for disability improved differentiation between people reporting isolated non-specific symptoms [‘Somatic’ (13.0%), and ‘Worried’ (14.0%)] and psychopathological symptoms [‘Subclinical’ (8.8%), and ‘Clinical’ (3.3%)]. Classes showed distinct associations with clinically relevant external variables [e.g. somatization: odds ratio (OR) 8.1–12.3, and chronic stress: OR 3.7–4.4]. The Subclinical class reported symptomatology at subthreshold levels while experiencing disability. No pure depression or anxiety, but only mixed classes were found.
An empirical classification model, incorporating both symptoms and disability identified clearly distinct cross-diagnostic subtypes, indicating that diagnostic nets should be cast wider than current phenomenology-based categorical systems.
Anxiety disorders are common, and cognitive–behavioural therapy (CBT) is a first-line treatment. Candidate gene studies have suggested a genetic basis to treatment response, but findings have been inconsistent.
To perform the first genome-wide association study (GWAS) of psychological treatment response in children with anxiety disorders (n = 980).
Presence and severity of anxiety was assessed using semi-structured interview at baseline, on completion of treatment (post-treatment), and 3 to 12 months after treatment completion (follow-up). DNA was genotyped using the Illumina Human Core Exome-12v1.0 array. Linear mixed models were used to test associations between genetic variants and response (change in symptom severity) immediately post-treatment and at 6-month follow-up.
No variants passed a genome-wide significance threshold (P=5×10–8) in either analysis. Four variants met criteria for suggestive significance (P<5×10–6) in association with response post-treatment, and three variants in the 6-month follow-up analysis.
This is the first genome-wide therapygenetic study. It suggests no common variants of very high effect underlie response to CBT. Future investigations should maximise power to detect single-variant and polygenic effects by using larger, more homogeneous cohorts.
Approximately half of the variation in wellbeing measures overlaps with variation in personality traits. Studies of non-human primate pedigrees and human twins suggest that this is due to common genetic influences. We tested whether personality polygenic scores for the NEO Five-Factor Inventory (NEO-FFI) domains and for item response theory (IRT) derived extraversion and neuroticism scores predict variance in wellbeing measures. Polygenic scores were based on published genome-wide association (GWA) results in over 17,000 individuals for the NEO-FFI and in over 63,000 for the IRT extraversion and neuroticism traits. The NEO-FFI polygenic scores were used to predict life satisfaction in 7 cohorts, positive affect in 12 cohorts, and general wellbeing in 1 cohort (maximal N = 46,508). Meta-analysis of these results showed no significant association between NEO-FFI personality polygenic scores and the wellbeing measures. IRT extraversion and neuroticism polygenic scores were used to predict life satisfaction and positive affect in almost 37,000 individuals from UK Biobank. Significant positive associations (effect sizes <0.05%) were observed between the extraversion polygenic score and wellbeing measures, and a negative association was observed between the polygenic neuroticism score and life satisfaction. Furthermore, using GWA data, genetic correlations of -0.49 and -0.55 were estimated between neuroticism with life satisfaction and positive affect, respectively. The moderate genetic correlation between neuroticism and wellbeing is in line with twin research showing that genetic influences on wellbeing are also shared with other independent personality domains.
Impairment of response inhibition has been implicated in attention-deficit/hyperactivity disorder (ADHD). Dopamine neurotransmission has been linked to the behavioural and neural correlates of response inhibition. The current study aimed to investigate the relationship of polymorphisms in two dopamine-related genes, the catechol-O-methyltransferase gene (COMT) and the dopamine transporter gene (SLC6A3 or DAT1), with the neural and behavioural correlates of response inhibition.
Behavioural and neural measures of response inhibition were obtained in 185 adolescents with ADHD, 111 of their unaffected siblings and 124 healthy controls (mean age 16.9 years). We investigated the association of DAT1 and COMT variants on task performance and whole-brain neural activation during response inhibition in a hypothesis-free manner. Additionally, we attempted to explain variance in previously found ADHD effects on neural activation during response inhibition using these DAT1 and COMT polymorphisms.
The whole-brain analyses demonstrated large-scale neural activation changes in the medial and lateral prefrontal, subcortical and parietal regions of the response inhibition network in relation to DAT1 and COMT polymorphisms. Although these neural activation changes were associated with different task performance measures, no relationship was found between DAT1 or COMT variants and ADHD, nor did variants in these genes explain variance in the effects of ADHD on neural activation.
These results suggest that dopamine-related genes play a role in the neurobiology of response inhibition. The limited associations between gene polymorphisms and task performance further indicate the added value of neural measures in linking genetic factors and behavioural measures.
To compare commonly used dietary screeners for fat intake and fruit and vegetable intake with 24 h dietary recalls among low-income, overweight and obese African-American women.
Three telephone interviews were completed; measures included two 24 h dietary recalls (a weekday and weekend day) using the Nutrition Data System for Research software, the Behavioral Risk Factor Surveillance System’s (BRFSS) Fruit and Vegetable Consumption Module and the National Cancer Institute’s (NCI) Percentage Energy from Fat Screener.
Participants were recruited from three federally qualified health centres in south-west Georgia, USA.
Participants (n 260) were African-American women ranging in age from 35 to 65 years. About half were unemployed (49·6 %) and 58·7 % had a high-school education or less. Most were obese (88·5 %), with 39·6 % reporting a BMI≥40·0 kg/m2.
Mean fruit and vegetable intake reported from the 24 h dietary recall was 2·66 servings/d compared with 2·79 servings/d with the BRFSS measure. The deattenuated Pearson correlation was 0·22, with notable variation by weight status, education level and age. Mean percentage of energy from fat was 35·5 % as reported from the 24 h dietary recall, compared with 33·0 % as measured by the NCI fat screener. The deattenuated Pearson correlation was 0·38, also with notable variation by weight status, education level and age.
Validity of brief dietary intake measures may vary by demographic characteristics of the sample. Additional measurement work may be needed to accurately measure dietary intake in obese African-American women.
The correspondences between the names in the Scylding genealogy at the beginning of Beowulf and three names in the upper reaches of the genealogy of Æthelwulf in the Anglo-Saxon Chronicle, Beaw, Sceldwa and Sceaf, frequently appear in arguments for a late dating of Beowulf. But these arguments overlook many aspects of Æthelwulf's genealogy that disrupt their case for a late dating. As H. Munro Chadwick pointed out over a century ago, the forms Sceldwa and Beaw found in the Chronicle for Scyld and Beow are not West Saxon spellings, and the -wa suffix of Sceldwa and Tætwa suggests that these forms may be archaic. Thus spelling alone indicates that these names were probably copied from an older, non-West Saxon text. Furthermore, the very presence of these names in the royal pedigree is puzzling. On one level the presence of Scyld is easy to explain: Scyld and the Scyldings were famous in heroic legend, and his inclusion in Æthelwulf's pedigree provides reflected glory for the West Saxon dynasty and implies genealogical, political and cultural connections between the West Saxons and the Danes that could be useful for Alfred and his heirs to foster. But on another level his inclusion is rather surprising: according to genealogical conventions, the presence of Scyld implies that the West Saxon royal family is a cadet branch of the Scylding dynasty, and is thus potentially subordinate to Scandinavian rulers in England claiming direct descent from Scyld.
Since the date of the Beowulf manuscript is widely agreed upon, the very question which prompts this volume (and the conference it derives from, and even the 1980 conference with its 1981 proceedings volume) must assume that the date of the poem may not be the same as the date of the manuscript. It is certain that there must have been a moment of first inscription for the poem, and that the time and place of that moment remains a central point of interest for students of the poem. In this essay, I will bring new evidence to bear on this venerable question, and my argument shall be that Beowulf is metrically conservative according to a variety of independent metrical criteria. Further, I will suggest that that conservatism is so varied and consistent as to strongly indicate that the original version of Beowulf must be placed among the very earliest of the longer narrative Old English poems that survive, probably in the eighth century.
Of course, it remains true, I believe, that the moment of inscription is only one of the moments of interest which might engage modern scholars of the poem. As I argued in Authors, Audiences, and Old English Verse, our focus on authorship (and on moments of authorship) may sometimes cause us to lose sight of what can be gained by also considering audience, and I proposed there two later audiences for Beowulf, one located at Alfred's Wessex court in the late ninth century, and another, sometime around the turn of the eleventh century, perhaps in Canterbury, represented most clearly by the author of Maldon.
As the introduction to this collection makes clear, the various forms of linguistic and metrical evidence bearing on the dating of Beowulf point to a date of composition fairly early in the Anglo-Saxon period. In his article for The Dating of Beowulf in 1980, Thomas Cable proposed a rough guide to the metrical dating of poems using the incidence of type C, D, and E verses, which decline in frequency over the Anglo-Saxon period. Cable's criterion places Beowulf toward the beginning of a relative chronology. Since then, much additional metrical and linguistic evidence has been gathered that places Beowulf in the early to mid-eighth century. R.D. Fulk's A History of Old English Meter is the most substantial work of this kind, for it examines the presence of archaic metrical features through-out the corpus of Old English poetry and finds that Beowulf is by far the most archaic poem. Since that work, other scholars have written articles on individual metrical or linguistic features of the poetic corpus, which have corroborated the conclusions that Fulk so carefully reached.
Some scholars, however, remain dubious about the reliability of this type of evidence. At this point, the force of linguistic scholarship is too formidable to be undermined by the doubts raised by E.G. Stanley, who urged that the poem should not be dated by means of sundry linguistic oddities that could well be scribal error or just a few bad lines.
From the publication of the poem's editio princeps in 1815 to the emergence of the present collection two centuries later, few topics in Anglo-Saxon studies have generated as much speculation and scholarship as the dating of Beowulf. Marshaling disparate forms of evidence and argumentation, scholars have assigned dates to Beowulf that range from the seventh to the eleventh century. Various individuals have been unpersuasively identified as the author of Beowulf and dozens of kings, clerics, and contexts have been associated with the poem's genesis. Scholarship on the dating of Beowulf is markedly uneven in quality: alongside sober and thoughtful argumentation, there has been a great deal of improbable hypothesizing about the author of the poem or the milieu in which it was composed. Awareness of the qualitative differences in the scholarly literature is tacitly registered in the relative frequency with which publications are cited, but these differences have rarely received explicit discussion. This introduction to the dating of Beowulf controversy examines the changing standards of evidence, methodology, and argumentation that have attended this topic, particularly in the past thirty years. The dating of Beowulf has not been a static or monolithic subject, but has undergone considerable change in the disputes it connotes and the practices it encompasses. In the following account, emphasis will be given to the reasons for prevailing opinions rather than to the multiplicity of opinions as such.